Zig

Get a Header Field from an Alternative Body

Demonstrates the Chilkat Email.GetAltHeaderField method, which returns the value of a header field within the Nth alternative body's MIME sub-part. The first argument is the zero-based alternative index; the second is the header field name. This example builds a message with plain-text and HTML alternatives and reads the Content-Type of the first alternative.

Background: A multipart/alternative message is a tree: each alternative body is its own MIME sub-part with its own little header block (Content-Type, Content-Transfer-Encoding, etc.). The top-level Email header methods read the message headers, whereas GetAltHeaderField reaches into a specific alternative's sub-part — useful for inspecting exactly how each representation is typed and encoded.

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const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // Demonstrates the GetAltHeaderField method, which returns the value of a header field
    // within the Nth alternative body's MIME sub-part.  The 1st argument is the zero-based
    // alternative index; the 2nd is the header field name.

    const email = try chilkat.Email.init();
    defer email.deinit();

    // Create an email with plain-text and HTML alternatives.
    email.setTextBody("This is the plain-text alternative.", "text/plain");
    email.addHtmlAlternativeBody("<html><body>This is the HTML alternative.</body></html>") catch {};

    // Get the Content-Type header of the first alternative body (index 0).
    const ct = try email.getAltHeaderField(alloc, 0, "Content-Type");
    std.debug.print("Alternative 0 Content-Type: {s}\n", .{ct});
}